Map Projections

 

Cartography is the art and science of making maps. Before the days of computers, satellites, and digital media, cartographers had to create maps using math, art, and navigation skills. Here are some basic types of map projections you will see throughout the class. Don't forget about the parts of the map (TODALS) and how to read different types of maps.

 

Cylindrical Projection

A cylindrical projection map is the most common type of map that we see. Imagine placing the movie screen around the globe in a cylinder shape. The projection that results is depicted in this image. Notice that areas close to the equator have very little distortion. However, the closer to the poles that one travels, the more distorted the map becomes. In this example, Greenland appears to be many times larger than it really is.

 

 

Conic Projection

A conic projection map is created by placing a cone shaped screen on a globe. The resulting projection is more accurate than the cylindrical projection map discussed above. However, the further we travel down the map, the more distorted and less accurate the map becomes.

Plane Projection

A plane projection is created by placing an imaginary screen directly above or below a globe. The image that would result is called a plane projection. This type of map projection is not commonly used.

 

 

 

Interrupted Projection

There are many different types of interrupted projection maps. These types of maps try to depict the continents as accurately as possible by leaving blank space in the less important areas of the map, such as in the oceans.

 

 

Shape Versus Size – Conformality Versus Equivalency

Each of the map projections previously discussed as well as any other type of map projection must consider two important factors. What is more important, depicting the accurate sizes of objects on the map, or depicting accurate shapes of these objects? The challenge is that you cannot have both. The more accurately you depict shape, the less accurate will be your depiction of size, and vice versa.

 

 

A map which portrays shape accurately is called a conformal map. Conformal maps are useful in that they help us understand the true shape of the items on the map. However, these maps have many drawbacks. A conformal map tends to get quite distorted, especially towards the top and bottom of the map. This creates problems with scale. The scale may be accurate near the equator, but the further one travels form the equator, the less accurate the scale becomes.
 

Hybrid Maps

Many maps are neither entirely conformal nor entirely equivalent. By blending both conformality and equivalency, we can create a map that balances the distortion of both size and shape.

Isolines

In Geography, it is often necessary to describe distributions on a map. Let's consider an example that most of us are familiar with. Have you ever watched the weather report on your local nightly news? One of the important jobs of a meteorologist, or weatherman / weatherwoman, is to show their viewers the distribution of temperatures.

Meteorologists use isolines to quickly show these temperature differences on a map. The hottest areas are often colored red, the warm areas yellow, and the cold areas blue. Isolines are effective because they very quickly communicate the distributions being examined.

 

Map Projections Assignment:

Look at the different types of map projections and maps. Complete the chart by describing the various characteristics of the maps and any distortions shown. Make sure you take notice of the shape of the map projection, what pieces are distorted, and what purpose the map could be used for.

 

Map Projection Exercise.docx